When a bone is fractured, it is often necessary to hold the fragments of the bone together to allow for correct healing. If this is not done, problems such as misalignment or poor healing can occur.
A conventional means for fixing fracture fragments is an external fixator, which typically takes the form of a steel or other material rod spanning across the fracture which is fixed to the bone fragments using pins. The rod is located outside the body, while the pins penetrate the skin and are fixed in the bone. This invasive technique involves surgery, and as such there is a risk of infection of the soft tissue or bone, and further there is a risk of complications arising from the surgery.
A further disadvantage of conventional external fixators is where the fixator spans a joint, such as the wrist or ankle. The steel or other material rod may not be articulated, thereby preventing movement of the joint.
Articulated fixators are known, but these have disadvantages as well. Alignment of the articulation with the joint can be difficult if not impossible, due to articulation of the fixator not being in the plane of the joint line axis. Known devices do not allow movement in the joint's plane of motion. For example, the position of the articulation of the fixator is dependent on the position of the pins drilled in the bone which can only be drilled in a limited number of positions. Furthermore, known articulated fixators also have the disadvantage that if the fractured joints are moved in fracture situation, this will disturb the fracture position. In particular, known devices allow for multidirectional movement, including rotation, thereby allowing the fracture position to slip.
U.S. Pat. No. 4,677,971 discloses a wrist splint for the treatment of soft tissue injuries, as a splint after surgery or in fracture treatment of small bones of the wrist (carpal bones). However, the device does not have rigid members connected by an articulation piece according to the present invention. Furthermore, as with other known devices, the device in U.S. Pat. No. 4,677,971 is not suitable for treating long bone fractures because the articulation piece is not at the fracture site or joint level and does not allow movement in the joint plane.
In certain locations, such as for a fracture of the radial bone, the patient's thumb may prevent suitable alignment of the steel rod and the articulation. This problem has been addressed to a certain extent with ring external fixators, such as Ilazarov. However, such fixators necessitate a number of invasive pin placements and lead to a very big and cumbersome fixator.
It is an object of the present invention to obviate or alleviate these and other disadvantages of conventional fixators. It is a further object of the invention to provide a non-invasive external fixator, which permits movement of a joint near the fracture site and also allows for fracture reduction and aids fracture manipulation.